The invention is an improvement of another invention patented by the same inventor on Jul. 3, 1984, under U.S. Pat. No. 4,457,416. That invention, entitled a "LASHLESS SOCKET DRIVE", utilized the roller bearing ramp-up drive mechanism to create the unidirectional and reversible, lashless drive of the instant invention. That wrench has been produced and works quite well.
The above-mentioned patented wrench is of the type that replaced reversible socket wrench drives characterized by pawl and ratchet drive mechanisms. Drives of this type are represented in U.S. Pat. Nos. 4,485,700, 4,512,218, and 4,631,988. The roller ramp-up mechanism, being somewhat more finely machined than the ratchet, virtually eliminates all lash or play inherent in the prior, ratchet-based systems. In a ratchet-based wrench, when working in confined spaces, there may not be enough space to move the wrench in the freewheel direction even far enough to engage the next ratchet tooth, making it impossible to use the wrench.
A substantially lashless drive utilized by applicant in his prior patent, on the other hand, will work in any space, no matter how confined, provided the wrench handle can move at all. For all practical purposes, there is no play or lash whatever. The roller bearings are pressed tightly into the converging ends of the ramp spaces in which they reside, and upon the handle being rotated in the drive direction, the drive immediately delivers torque to the rotor on which the sockets are mounted.
Other wrenches using the roller ramp-up mechanism have been developed. These wrenches basically fall into two categories. Both types require that the rollers seat in ramp spaces of which one side is circular or cylindrical (depending on whether ball or roller bearings are used), with the other surface being a ramp. The ramp provides the drive, and the cylindrical surface provides the freewheel.
The first type of wrench defines the cylindrical, freewheel surface on the rotor socket drive mechanism. The ramps are defined in the radially outer encasing housing, defined in the head of the wrench, which is connected to the handle.
It is easier to make a reverse mechanism for wrenches of this type, in which the inner rotor is cylindrical and the outer rotor chamber defines the ramps. Because the ramps are not rotational relative to the head and handle of the wrench, the ball or roller bearing reverse mechanism can be simply incorporated in the handle, and merely flipping a bearing keeper toggle mounted on the wrench head re-defines their position relative to the stationary ramps.
However, this type of wrench is not nearly as strong, nor does it provide the positive drive, as wrenches having the ramps on the internal rotor, with the outer chamber defining the cylindrical surface. The much smaller diameter of the cylindrical rotor surface compared to a cylindrical inner surface of the mounting chamber provides less gripping surface and is much easier to slip in the wrong direction should grease get on the cylindrical surface.
For this reason, the second type of bearing-based wrenches which reverses the positions of the ramps and the cylinder, having the ramps defined on the rotor and the cylindrical surface on the wrench head, is superior. However, an additional problem is encountered in that no longer can the reverse mechanism be stationary relative to the wrench. The reverse mechanism now must rotate with the rotor, because the rotor defines the ramps with respect to which the bearing orientation must be altered.
Applicant's first wrench fell into the second classification. The reverse mechanism in fact rotates with the drive rotor, and although the wrench works quite well, nonetheless generally a second hand is required in order to put the wrench into reverse drive. Another wrench in this second category is disclosed in the Pratt patent, issued May 10, 1949 under U.S. Pat. No. 2,469,572. Although this wrench has ramps on the rotor, the reversibility is accomplished by temporarily seizing up rotation of the bearing keeper or cage while the wrench is rotated, thus rotating the bearing keeper relative to the central rotor. With this type of mechanism, a single hand may be used to reverse the direction of the drive. However, the drawback of Pratt is that it incorporates a certain amount of play into the wrench as it is being reversed, inasmuch as the bearing keeper has gears or teeth which must be engaged by the arresting mechanism, and the wrench then turned to drive the bearings into the reversed position. A necessity therefore, reversal requires not only a dual motion, but necessarily causes play when reversing directions.